/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.accumulo.core.client;

import org.apache.accumulo.core.data.Range;

/**
 * Scans a table over a given range.
 *
 * "Clients can iterate over multiple column families, and there are several mechanisms for limiting
 * the rows, columns, and timestamps traversed by a scan. For example, we could restrict [a] scan
 * ... to only produce anchors whose columns match [a] regular expression ..., or to only produce
 * anchors whose timestamps fall within ten days of the current time."
 */
public interface Scanner extends ScannerBase {

  /**
   * Sets the range of keys to scan over.
   *
   * @param range
   *          key range to begin and end scan
   */
  void setRange(Range range);

  /**
   * Returns the range of keys to scan over.
   *
   * @return the range configured for this scanner
   */
  Range getRange();

  /**
   * Sets the number of Key/Value pairs that will be fetched at a time from a tablet server.
   *
   * @param size
   *          the number of Key/Value pairs to fetch per call to Accumulo
   */
  void setBatchSize(int size);

  /**
   * Returns the batch size (number of Key/Value pairs) that will be fetched at a time from a tablet
   * server.
   *
   * @return the batch size configured for this scanner
   */
  int getBatchSize();

  /**
   * Enables row isolation. Writes that occur to a row after a scan of that row has begun will not
   * be seen if this option is enabled.
   */
  void enableIsolation();

  /**
   * Disables row isolation. Writes that occur to a row after a scan of that row has begun may be
   * seen if this option is enabled.
   */
  void disableIsolation();

  /**
   * The number of batches of Key/Value pairs returned before the {@link Scanner} will begin to
   * prefetch the next batch
   *
   * @return Number of batches before read-ahead begins
   * @since 1.6.0
   */
  long getReadaheadThreshold();

  /**
   * Sets the number of batches of Key/Value pairs returned before the {@link Scanner} will begin to
   * prefetch the next batch
   *
   * @param batches
   *          Non-negative number of batches
   * @since 1.6.0
   */
  void setReadaheadThreshold(long batches);
}
